When Daylight Comes
by Fifteen1413
Summary: 5250K Blackbody Spectrum. Primary absorption lines in Hydrogen, Helium, Oxygen, Calcium, Magnesium, Mercury, Iron, and Sodium. 13% blue light removal from Rayleigh scattering. If my skills with a sword won't cut it, I'll just have to build a sun instead! [Features OC's, possibly divergant timeline, writing blind so I don't know exactly what's next either. M for violence and gore.]
1. Chapter 0: Derivative Works

Greetings. The short blurb we are allowed to preface our stories with is insufficient to provide much of a real taste to the work I plan on making here. My writing style is not good at concision, so I felt that this space would be better and more informative to you as to what you might be getting yourself into with this story.

I am writing this purely for fun. I just really love the series and want to play with the ideas that it touches on. For this reason, although I will be running primarily with OC's set in the same world, these OC's may (let's be real, will) have strong similarities to some of the characters from the series itself – mainly, the relationship between my brother and sister main character pair and their starting situation is very similar to Tanjiro and Nezuko. I promise, as you will see, they will be differentiated – and special in a different manner.

This story will be soaked in science. I'm a mechanical engineer, transhumanist, and techno-optimist. Because of that, if you want to see people winning fights because they just tried so gosh darn hard, that will happen but not nearly as often here. Mostly, people will achieve victory through application of clever solutions both environmental and often technological. But I will be respecting the source material – otherwise, why bother writing a fan-fiction, just make your own similar work – so sometimes the hotblooded baddass approach will succeed when others fail!

I have only watched the anime. I have and will continue to do some research on the world as it has progressed in light-novels and manga, but the vast majority of my canon is the anime. If I do or say something that contradicts a point brought up later in the story, I am sorry, but I'm here to have fun first and foremost.

A much better synopsis:

Satoru and Haru Noguchi live with their father in a small family home not far outside of Tokyo. Satoru wants to help his father earn money to keep food on Haru's plate, but he is hampered by the will of the gods – Satoru is physically weak due to an unknown medical condition that causes him to easily lose balance and get suddenly and desperately lightheaded whenever his heartrate exceeds 120 BPM. In his spare time, Satoru and Haru apply themselves mentally, hoping to take advantage of this industrial world to make up for their physical inferiority. Their lives are hard, but stable and happy. That happiness is shattered when, one stormy night in September of 1913, their father is murdered by a demon and Haru is turned into one. It seems like the start to a familiar story – but due to his physical condition, Satoru is in no position to become a demon slayer! Luckily, he and his sister share one remarkable trait, one which has become only ever more important as industrialization sweeps Japan – keen, cutting intellects. But, in a world still largely dominated by strength, a world still stuck in the middle of the transition to technological supremacy, will it be enough to make up the difference?

If this sounds interesting to you, read on! I can promise that I will do my best to make things exciting. This won't be a physics lecture – it's a proper story. I hope you can find the adventures of Satoru and Haru entertaining, thoughtful, and fun!


	2. Chapter 1: A Dark And Stormy Night

Lightning flashes fill my vision. I can hear them, closing in all around me. Claustrophobic. I struggle to sit up, but it feels like there's a weight on my chest. I can't breathe. Above me, I see a shape barely visible in my fluttering eyes. A – a demon! Sitting my chest, staring at me. My heart races. Terror fills my blood. It's all I can do to not immediately lose consciousness again, my head beginning to spin. What – what could possibly…

"Big brother~." I hear her sweet voice, and my fear almost instantly fades. "Shhh. It's just a hypnogogic hallucination~." I feel her soft hand gripping mine. My mind clears, panic shatters. Of course. Sleep paralysis. The mind plays tricks on you to explain why you can't get yourself to move, to explain the weight on your chest caused by your own sympathetic nervous system being in control of your body. It invents creatures, usually sitting upon your chest, superimposed into your confused visual field to give you a reason for your lack of control. Within seconds, it passes, as you reclaim conscious control of your body.

Demons, of course, aren't real.

I calm down. My breathing returns to my control, my heart stills. My eyes re-open, alighting upon the kind, gentle, smiling face of Haru. Her soft green eyes cleanse my soul, filling me with a deep feeling of safety. I reach out, gently pushing her dark chocolate brown hair out from around her face.

"What are you doing here, Haru?" I ask, as softly and non-confrontationally as I can manage.

"I know you get nightmares when there's lightning." Her nose cutely twitches as she sniffs the air. "Must be the ozone~." Her smile is infectious, and I can't help but start smiling too.

"It's probably the light and sound, Haru. Not everything is chemistry." Haru huffs, puffing out her cheeks.

"Yeah, but _nearly_ everything is. Why would you think it's the light and sound combo; wouldn't that just be likely to wake you? Not everything is physics~!"

"Okay, okay, sorry." I put a hand up, fending off her pouty face. "Maybe it's the ozone."

We look at each other for a moment, before both laughing gently. "We could do an experiment. I bet I can make ozone here, and light and sound is easy." I muse, and Haru shakes her head adorably.

"No, no, because either way it'll give you nightmares!" She declares. "We'll just block out all three, and then we won't have to worry about it." Haru starts tapping her foot. "I wonder, how do you break down ozone…"

A crashing noise emanates from the floor below, followed by a rapid scrambling noise. Haru jumps. I laugh as she sits down, frowning. "W-what was that! It sounds like something is moving!" Haru says, tugging on my shoulder. The scrambling noise happens again and she covers her ears. "Ahh~!"

"Shhh…" I say, sitting up from my bed. It is no struggle for me to make it to the window, but opening it does prove a challenge. Slowly, carefully, I force it open piece by piece. The scrabbling noise happens one last time, and then – I grab the branch of the nearby tree with my hand. Realization crosses Haru's face, and she smiles brightly. Then frowns again.

"I would have figured it out eventually."

I muss her hair. "I'm sure you would have. But I don't want you scared for that long."

"It's just… the dark and deep storm, rising so suddenly… it reminds me of the story of the demon storms." Haru says gently. "I guess I can't help but believe a little bit, huh?"

"Of course! Stories stick with us deeper than facts do, sometimes. That's natural. But, of course…"

Demons, of course, aren't real.

Haru nods, motioning for me to get back into bed. "You should rest! I don't want you to make yourself sick moving around too much."

"I'm not that fragile anymore, Haru. I can open windows and walk around." I say, indignant despite myself.

"I know… but I just don't want anything bad to happen to you." Haru leaps up gracefully to the windowsill, pulling it shut for me. "I worry about you sometimes."

"I know." I sigh. I wish she didn't have to. I didn't enjoy my condition. But I was getting stronger. I wasn't bedridden. I could walk, I could carry light objects, I could even run a short way now. And my condition had never once gotten worse. I was getting better – I didn't want to see Haru worry any more.

There is a slight jingle from an inside room as a door is opened. "Home so late again." Haru says. "He works so hard for us." I nod, unable to fully expunge my shame. I am 15, 16 in only 2 weeks. I should be helping him, helping provide for our family. As the oldest surviving son, it is my duty and roll. But my body prevents me from doing any meaningful labor.

Haru grabs my hand. "He does it for you happily, Satoru. He works harder so you don't need to feel bad. And, you're going to pay him back one day, right?" She gestures to the makeshift equipment in the room at large, trinkets of electric and mechanical science that comprise my bedroom lab. "You're going to invent something big and important, and then we won't have to worry about money ever again."

"I hope I can, someday." I say, but I know she's right. Father works late every day because he never wants me to feel like I have to work to make ends meet. He wants me to concentrate on my studies, and go to the university of Tokyo when I turn 18. I will never be good for physical labor. But it's the dawn of the twentieth century; there is a space in this industrial world for people like me to make a difference and impact.

"Or maybe I will, and then neither of you will have to worry!" Haru says, grinning, her eyes closed in a smile. Her short plain kimono smells of Sulphur and Bromine, residues of her most recent chemical experiment. She takes to chemistry at least as well as I do to physics, perhaps more so. She has no future in the chemical sciences – no universities will take a woman. But that doesn't change the irrefutable fact that she was good at it.

"I'll sing you a song." Haru declares as I lay back down in the bed. "And then you'll fall right to sleep, and won't have any more nightmares. Because I'll be right there."

I nod. That logic, of course, was irrefutable. How could one be scared, with Haru around?

Her green eyes slide shut, and from her lips slowly pours a sound that angels could only dream to match. I let it carry me for a moment, sliding into the bliss of unconsciousness, carried off by her precious, calming tones.

I awake suddenly to her scream.

I'm out of the bed before I process what has happened; my reflexes are only to protect. Downstairs. Left of the hallway, towards the back. Our house is not large, it can only possibly be one room. Behind me, I flick on the electric lighting. Expensive to run, so infrequently used – but now certainly called for it. Night turns to day in an instant. Nothing is in my head except Haru's scream. I don't see the blood until I slip in it, faceplanting in a rush.

My eyes are filled with red. The walls are stained with it, painted everywhere like a work of surrealist art. It drips, still fresh, mocking the rain still gently falling outside. The smell fills the room, nauseating. I look in through the open paper door from the hallway outside upon the macabre sculpture, the ode to suffering and torment that has taken its poison root in my home, using the body of my father as its medium. My eyes fly wild. Something did this. The scream was seconds ago. They had to be here somewhere. Fight, flight, freeze. But I couldn't do any of it, not when I couldn't even see what had done the unspeakable thing.

Then I see the _eyes_. Glowing softly in the darkness, they simultaneously gave off an aura of utter poise and perfection, and an endless void of malice which threatened to swallow my mind simply by looking into them. Their mere presence pushed my heart to dangerous highs – the adrenaline froze in my blood, and all chance of holding onto myself faded in a split instant. I could already feel myself dropping to the floor. Even obscured by the darkness, I could feel a smile of infinite malice pierce me, shattering whatever meek will I had left. As it turned away, I could tell with utter certainty that its barer could have extinguished me with a snap of their fingers – and only wasn't because they thought I would suffer more this way.

My mind clawed its way shut, retreating from the impossible scene before me. And, it did have to be impossible. A nightmare. Nothing like this could have possibly been real – after all…

Demons, of course, aren't real.


	3. Chapter 2: Ringing Bells

I flutter to consciousness all of fifteen seconds later. I passed out not from a demonic spell or machination, but due to my own sickly body and heart. In all this hell, my condition may have been the thing to save my life – it made me appear frailer and more hopeless than I actually was. Without it, I was sure, sure as anything, that those eyes would have swallowed me whole right where I stood.

I could taste the sharp metallic tang of blood on my lips and tongue, feeling the fading heat on my cheek. I didn't want to open my eyes. I knew. I knew it wasn't a dream. And I didn't want to face it. I shivered there, barely even letting myself breathe. I had never been more certain that, if I was to move, those eyes would come back and slit me up slowly and vindictively as another piece of demonic art. I would lay here a day, two days, three – until either I could bare my thirst no longer, or someone came to find me. Perhaps even dying of thirst would be preferential to facing that deep, illimitable darkness again.

Haru made a small, pained sound, and I was to my feet before my brain had quite processed what my body was doing. I couldn't pinpoint the noise – I couldn't see her. All I could see was the blood, the inside-out body of what had at one point been my father. As quickly as I had risen, I dropped back down to my butt. I couldn't process anything. Nothing at all. Already, I felt the fog swirling at the edges of my mind. I was about to pass out again, already. Perhaps I was just frail and hopeless; perhaps there had been no pleasant deception to my collapse.

"B-burns…" Haru's small voice says again, and I somehow manage to focus. Below. She's trapped below Father's body. I know what to do. Lift it off, or even just push it to the side, allow her to move again. But I can't. I can't move at all. It's just too much. I can't touch his cooling skin, covered in his blood. I wouldn't even know where to grab – I barely recognize his form, warped by some macabre demon art, distorted and distended, as if his chest expanded and melted at the same time.

"It burns my arm… I can feel it spreading…" Haru says meekly, and with the force of 1000 reciprocating steam engines, I push myself up against the mountain laying on my back.

"W-" I try to speak, but it doesn't come out. Just a gurgle. I shudder there, unable to move.

"S- Satoru? Are you there?" She says, pain obvious in her voice.

"I - I'm here!" I yell. "W-where are you! I don't want to push the body the w-wrong way, I'm not strong enough to move it twice!" Tears stream down my face, leaving clearing tracks in the blood that soaks my clothes and skin.

"Something is in me, Satoru." She says, and I can feel my world shattering. "I think it's whatever killed Father. I think it's in the blood." She pauses, panting, whimpers of pain. "I- it's in my arm. It got in through cuts on my arm. It's spreading from there. S-so if you drank a little you might be okay."

"Where -!" I yell incoherently, unable to form words. Her voice is too soft. I can't tell where under Father's body - Father's corpse, she is.

"I'm going to die, Satoru." Haru says, her voice as flat aside from the undercurrent of strained pain. "I'm pinned, my bloodflow is restricted, but I have at most 50 seconds until whatever it is spreads through my entire bloodstream. I can feel a heat like nothing else ripping through me – my cells are burning. When this reaches my head, I will not survive it."

No.

"You need to run." She says weakly. "You need - you can't die too."

No.

"Satoru? B-big brother?" Her voice sounds like it comes from beyond a wide and stormy sea, all but incomprehensible. "Y-you need to live. P-please."

"NO!" In a flash of fury, I wrench what remains of my Father's corpse off of the floor and throw it across the room. It moves barely two meters, a pathetic ultimate showing – but enough to totally clear Haru of his pinning body. I can feel my muscles snap, but I ignore it. It doesn't matter. I need – I need – Haru –…

I wake up another fifteen seconds later. Haru has passed out, but she's breathing. Her veins look horrible, like an acid had been injected into her blood – but she's still warm, still together. She hasn't died. I can still save her. I can –

Haru's eyes open. There is nothing in them except hunger. Only my startled stumble back saves me; she tears at the open air that I had previously occupied with sharp claws that leave red afterimages in the air as they split it. She lets out a feral roar of insatiable thirst that is both alien in deeply primal ways, and yet disgustingly identifiable as her voice.

She's on top of me in the next second. I can feel her nails bite my skin, drawing blood. I can't resist her. Her strength completely overwhelms me. There is nothing I can do to oppose her inhuman power. She licks her lips and drools, snapping at my neck, eager to take a bite. This is it. This is how the horror would end. I feel what little strength remains in my body leave me. Maybe this is how it was meant to be. If it's Haru, maybe dying won't be so bad. She knows human anatomy very well; it will be fast. That's all my body is good for in the end – just meat and blood. Perhaps this is just what someone too weak to protect their little sister deserved.

Meat and blood. My eyes snap open. My head barely dodges out of the way of Haru's teeth. She grazes my skin, leaving painful tares in it, but not hitting anything vital. I've gone limp; she's not grappling against my arms any more. They're free. With every gram of strength left in my bones, I reach despairingly to my side, my fingers desperately flexing, looking for the warm and wet.

I find it. Biting back my cries and begging for forgiveness, I yank the object forward, presenting it to Haru just before she makes her next strike, sure to be the last she'd need against prey as pathetic as me. Her eyes dilate for a moment, and then focus upon the proffered object – the arm of our now dead Father. Normally, there would be no amount of strength I could muster to rip something as well attached as an arm from a body, but whatever had been done to him had nearly melted his chest; the attack had severely softened the tissue. The flesh should have been soft enough - and, obviously, I had been right.

"Meat and blood…" I whisper, a desperate plea to whatever gods might still preside over this cursed world. Did it have to be still living prey? Did they feed on souls or lifeforce or… or…

Haru happily bites into the arm, sitting up and ceasing her crushing of my legs. I shudder in desperate relief. The physical was enough. With shuttering lips, I whisper a silent prayer, asking forgiveness from my Father. I knew well that he would much rather his already dead body be eaten than my still living one, but it still felt deeply wrong to allow to happen.

Haru was fast. Her teeth were as sharp as razor blades, rending the soft flesh with the ease of biting into a rice ball. For my part, it was all I could do to keep myself calm enough that my condition didn't knock me out a third time. I was all but spent in terms of energy, my muscles burning. I was covered in blood. I was weak and weary, and the young demoness in the body of my little sister was, if anything, in a better position now than she had been before. If she decided to go after me now, I didn't think I had anything left. It was honestly a miracle l that I made it this far.

Her teeth crunched bone. I shuddered at the sound. Good, I supposed. I wasn't completely deadened to everything yet. From behind her meal, her eyes stared out at me. Hunger. Nothing except hunger. I felt any last embers of hope barely clinging on in my broken soul extinguish before the tide of darkness. There was nothing left. I had done my best.

Then, as if delivered by the gods themselves, from the darkness emerged a single, golden spark. Dancing behind the hunger of Haru's eyes was a cutting intelligence. Somehow, I knew. Despite the filters of bloodlust and horrible appetite that lay between me and it, I knew that that intelligence wasn't malicious. Something of Haru still remained, somehow, fighting just as hard as I was, pushing against its prison now that I had, however temporarily, satiated the guards.

"P-Par…" She growled, shuddering. Digging nails deep into her own skin, she forced forward words from the depths of her soul.

"Pavlov."

Operant conditioning. Train a dog to associate the sound of a bell with the delivery of food, and it will salivate. Train one to associate the sound of a bell with an electric shock, and it will cower and flinch every time in hears the noise. She had a horrible hunger, one that tore her sanity apart to the level she could barely restrain herself from attacking her own brother after she had just eaten. But, train her to associate satisfying that hunger with some unpleasant enough stimulus…

I could tell she was not going to hold it together for long, and I wasn't about to waste the plan she'd torn her own mind apart to share with me. I turned and ran, not out, not away – up. To her room. To her chemicals. I could hear her follow me. Even her most desperate fighting had only bought me six seconds, but it would be enough. It would have to be.

By the time I threw open her door, she had covered half the lead. She was frighteningly fast – and I was depressingly slow. I didn't have time to look for anything specific. With a rush, I raised my left arm to defend my face as my right grabbed the first vial I could get my hands on. A beaker. Clear liquid. A concentrated acid or base? I could only hope.

Haru bit my left arm. I let her. Pushing through every scrap of pain, barely remaining conscious, I let her take a bite. And then, only once she had done so, only once she wasn't in attack mode but rather in eat mode – I had to get the association right – I hit her on the top of the head with the vial. It shattered over her, and she released me immediately. Her hair smoked and the skin on her scalp boiled. Her yell shook the house. I could see the sugars and oils in her skin pyrolyzing and turning into carbon on the spot. 12 molar HCL. I had hit her with 12 molar HCL. I needed to grab another. One stimulus would not make an association. I needed something else, while she was distracted. I needed - I could feel the fog clouding my head again. I fought it with everything I had, but it wasn't enough. Darkness closed around me, drowning me in its deep embrace.

Thirty seconds this time? 45? I pushed myself back up from the floor where I had collapsed. I was reaching an absolute limit. The next time I passed out, I'd probably stay down. Everything hurt. Blood dripped from where Haru had bit me. She had taken a whole coin-sized cut of my flesh with it, pure luck stopping her from having pierced any major arteries. My fingers stung from where even the smallest droplets of the fuming hydrochloric acid had touched them. I turned my head to the room. Haru had left. Presumably, she was going to eat more of Father – his body wouldn't fight back. I needed to use this as a conditioning opportunity. Stumbling to my feet, I searched the now scattered remains of the already small and scattered bedroom chemical lab. Concentrated hydrogen peroxide. Good for a strong conditioning. Hydrofluoric acid – no, it had to be weak, or it would have already dissolved the glass case it was in, being glass etch fluid and all. A syringe. Alcohol on the table – injected into the bloodstream directly, that would induce huge amounts of pain.

Last minute, something clicked in my head. No amount of conditioning would be able to override a deep enough hunger, certainly not one I could instill quickly. I needed to re-direct her, not stop her completely. Nodding curtly to myself, I grabbed a vial marked 'Q' as well, making my way downstairs with dread but determination.

Haru was there. She was licking blood off her fingers, vibrating with barely contained restraint. I was not stealthy. She noticed me instantly, and her rage and hunger won out upon seeing her tormenter. In a flash, she went for the body. Just as fast, I threw the 'Q' bottle at the body, spraying the entire scene, coating it all in a thin layer of concentrated Quinine.

The look of utter disgust on her face as she took her first bite was the most heartwarming, encouraging, beautiful thing I had seen tonight. Two bites, three – she didn't take a fourth, looking at the body as if it had betrayed her. She pooled slowly coagulating blood in her palm, drinking it – only to spit it out after the second sip. No pain, not nearly as strong of a deterrent. I'd much rather her eat people already dead than attack people still alive. But Quinine was a powerful bitterant, especially in such a high concentration.

She lunged at me again. If the corpse tasted bad, perhaps I – but, no. She bit my arm again, but I had already soaked it in the Quinine. As pure rage filled her eyes, I calmly poured the concentrated hydrogen peroxide down her back. Howling in pain, she stumbled backwards, sitting down in the room with a weighty thud.

Pulling her knees up to her chest, Haru began to weep gently. I watched her, ready to move, but I could already feel unconsciousness pulling at me. Would it be enough? Two was possible to form an association with, but still unlikely. Five, at least, to make sure it stuck. But I didn't think I could last that long. Could I hope it had been sufficient? Or would the next time I awoke, the final time, be under Haru's teeth?

There was nothing for it. I felt my knees give out below me, sinking to my side. Exhaustion wracked every pore of my body. My breathing broke, panting uncontrollably. My heart pulsed explosively in my chest. I couldn't keep it away any more than one could stop the dawn. It would be enough. It would have to be.


	4. Chapter 3: Flight of Fancy

"Wake up."

My eyes flutter open through layers of fog and hurt. I hungrily gasp at the air until my lungs feel fit to burst, a scream of shock and torment ready to erupt from my lips. A firm, warm hand covers it. My mute anguish hangs for a moment, and then I fall numbly silent.

Everything hurts. There is not a single pleasant sensation anywhere on my form. My arms feel as if flame has been injected into the muscles, my chest is raw and ragged from strain and impact. My legs pulse with freezing numb as if my bones were ice. My skin feels itchy everywhere, dried blood covering nearly all of it. Even the inside of my skull hurts, the anguish of half processed horrors chasing themselves inside my mind.

Above me, the owner of the scream-killing hand sits, my head in her lap. Her deep, near-black brown hair falls from her soft face in a cacophony of tangles matted with blood. Her strong emerald eyes have faded soft-jade centers now, drawn inward towards the predatory slits that now stand in place of her pupils. Her canines are large and pronounced, visible as small bulges beneath her lips. But, despite her dramatic change, the features had a clear, recognizable owner.

"Will you scream if I remove my hand?" Haru asks, and I can't help but whimper at the hardness in her voice. Choking down distress, I breathe in deeply three times through my nose before nodding a strong negative.

"Okay." She withdraws her hand gently, and I can breathe freely again. Coughing suddenly, I do my best to restrain any noises of pain. Haru's eyes seem to balefully shine out at me, examining my face with restrained interest.

"W-w-" It is hard to spit out the words, my throat dry and mind addled. "Where are w-we?"

"About 8 kilometers outside of Tokyo, south-southwest." Haru says simply. "I've carried you here. We need to wash off the blood, and I didn't want you to drown, so I woke you."

She's right; unsurprisingly, I am soaked in blood. We won't be able to go anywhere civilized until the blood is gone. Carefully, I examine our surroundings. The area here is lightly wooded, agricultural fields sprawling out on all sides. We are in a secluded patch of nature, just barely out of view. A small stream trickles through the grove, pooling in a pond just large enough to submerge a person in before continuing its journey to the sea.

I go to move, but my body refuses. I have overtaxed myself to near complete exhaustion - now that my adrenaline is gone, my whole body is starved of the energy it needs to run. It's a struggle to even keep thinking. Haru stares down at me for a moment, then sighs.

"You can't move, can you? Muscle burnout. You're out of glycogen." There is little emotion in her voice, but what is there is not kind. "Pathetic." She shakes her head. "I'll wash you."

"Haru…" I say weakly, hot tears pooling at the corners of my eyes. This… this wasn't like her. She tilts her head, looking at me.

"Yes, that was my name, wasn't it?" She says thoughtfully, picking me up lightly with inhuman strength. "Haru Noguchi. And you're my older brother, Satoru." She recites the information as if recalling facts from an encyclopedia. There is little connection to her words in her eyes. "I was born 6 June 1899, and have lived 14 years 3 months. We lived in a small family home just outside of Tokyo with our Father, a skilled blacksmith." She steps into the pool, lowering me gently into it. "You were born 19 September 1897, and have lived 15 years 11 ½ months." I can feel her hands rubbing my skin. Pain shoots through my left arm where she had repeatedly bitten me, and I let out a whimper. "You have an unknown medical condition that causes you to pass out whenever your heart rate rises above about 120 BPM, making it impractical to train your physical ability to any serious degree." I can feel the sharpness of her nails like razors on my skin. Around me, the water begins to flow red. "We were close with each other, often over our shared love of science. I specialized in chemistry, and you specialized in physics." The cold water rushes past my ears, making it difficult to concentrate on her words. "You were plagued with fears of the world due to your condition not allowing you to participate in it meaningfully; I would often sing to you to quell your nightmares."

There is nothing to her voice. To her, these statements are only facts, as boring and trivial as any other uninteresting list. Despite myself, I can feel my blood boil. Drawing on deep strength I didn't know I had, a yell of rage bubbles up in my throat.

"Stop it!" My voice is ragged but strong and forceful, cutting Haru off soundly. "What is all this to you? Why are you tormenting me with all the things you know but now can't feel!?"

"**Because I don't want to forget them." **

My anger shattered against her words like glass thrown directly from a kiln into liquid nitrogen. Raw, anguished emotion dripped from her voice, rage and fear and pain and sorrow of a magnitude so vast as to threaten to swallow my meager conscious in it. "I am **barely **grasping at the falling edge of my humanity, and I don't want to lose anything else." Tears bubble up around her suddenly vulnerable face, pure terror and loss dancing in her eyes. "You have **no idea **what I am dealing with. If I stop pushing for even a second, I will lose myself and **eat you. My mind** is being consumed as my body **agonizingly warps beneath my skin**. Please find it in yourself to forgive me for lacking emotion when desperately holding on to the last of my mind in **the only way I know how.**"

I don't speak after that, and neither does she. Her hands continue to rub down my skin, the cold water numbing the pain of the process as the stars slowly spin overhead. I can't tell what time it is. Nearly morning? Or has the night barely begun? There are no clues. Time has become immaterial in this nightmare. It is all I can do to lay in the pool, resting in my thoughts.

"I'm going to submerge your head on the count of three." Haru says, and I offer no response besides a single nod. I can see, now that I know to look for it, the immense pain and struggle written on her face. I strain to think of something to say, to apologize, but nothing comes.

"One… Two… Three." I take a deep breath and feel my head pass beneath the surface of the pool. Water clouds my eyes for a moment before they readjust to the environment. A thin red mist pervades everything around me, the remnants of the blood washed from our skin. Haru's form is warped further by the refraction of the water's edge, making her seem to tower immensely overhead. She keeps my body submerged easily with one hand, running her claws gently through my hair. I can feel the strands separate one by one between her fingers. Then, as I began to feel the light edges of burning in my lungs, I hear her begin to sing.

The water muffles and drowns out all but the strongest melody, but even still, I can recognize her voice. Soothingly, calmly, she fills my soul with trembling tones yearning to be free. I feel her ode to life and beauty overrun my mind as my body begins to starve for oxygen. I buckle and begin to squirm against her hand, reaching out to pull it off, but her strength is overwhelming. Her fingers gently stroke my scalp as my lips silently beg for air, releasing bubbles I can no longer contain. The music reaches a crescendo, a distant note like a flute being held in defiance of the sea, blackness closing in on my vision…

And then it falls silent.

I am lifted from the water. As soon as my lips break the surface, I gasp desperately for air. The hunger of it fills every corner of my being, every fiber of my soul. I force the last of my breath from my lungs, pulling for the cool damp air of the pool – and Haru's hand blocks my mouth. Mutely, I stare into her eyes, filling slowly with a cold, calming horror to quell the fire in my lungs.

"Hold your breath for me." She says gently, her eyes sharp. She stares me down for five seconds, and then slowly removes her hand from my lips.

It is hell. 90 seconds without air have already passed, and I don't have the strength to exercise, so I have never built up my ability to store oxygen. I push against even the darkness in my vision, but the struggle feels more than I can bare. Why? Why does she want me to hold my breath? What is she doing? But I don't fear now, at least – if she meant to kill me, she would have never let me up from the water, never taken her hand from my lips. She means to test me. I mean to pass the test.

117\. I lose to the pain in my lungs and the darkness swirling in the corner of my vision. I gasp twice, long heavy breaths, feeling flooding back to my mind. Shakily, I turn to look back at her. Her eyes glint in the darkness. They examine my face with calm disinterest and uncaring detachment. A small sneer rests on her lips. I can almost feel the malice radiating from her.

And then it breaks. It's almost like a transformation, her features softening, warmth flooding back into her face. She pats my head gently, the now clean hair free of blood sliding easily under her fingers. "I forgive you." She says softly. "You've suffered for me enough already." A flood of shame, conflict, fear and anger runs through me for a moment, but I let it flow out of me before my heartrate spikes. Calm. Calm is important for me, and I have become very good at it.

"I understand." I say, nodding my head low. "It's hard to ignore biological signals. You're strong for fighting it as much as you are. I was… I was just worried about you."

She doesn't respond outright, though the new softness to her features and concerned examination of my body speak loudly enough on their own. Her fingers find their way to my arm, poking the area where she had bit me. A decent chunk of the arm is missing there, though not huge; a polite, small bite. Teethmarks puncture the area around it, the wounds of her sharp canines still ringed in blood. The whole patch is bleached white. It only aches with a dull pain. "I soaked it in some of the leftover hydrogen peroxide." She says. "To stop sepsis and gangrene. I might have overdone it slightly and killed some of the surrounding flesh."

"As long as its not some kind of demonic curse…" I say, trying to force my mind to be active, to keep off the layers and layers of fatigue that cloud it. I couldn't think of a single thing to do about this situation. Nothing I had learned, nothing I knew, covered anything remotely like this. I half expected that I had gone crazy. This was an out of context problem, a black swan event. Something I was completely unprepared for. Demons weren't real. They were stories that people in the countryside told each other to explain wild animal attacks. They were unsubstantiated nonsense. And my sister had become one.

"Are you okay?" I ask numbly after a minute. Haru sighs, putting me down on the bank of the pool, leaning down to wash the blood from her own hair.

"No. I'm not sure I can be." Haru says. "I don't feel myself anymore. I feel… I feel like a warrior. I want to kill." She licks her lips, then shakes her head. "But I don't _want_ to kill, do you understand? It's like a hunger. It's not a moral choice." She sighs. "And I think I'm in control right now." An underhanded, half-happy smirk grows on her face. "Though I imagine we're going to need a lot more Quinine to keep it that way. Maybe some Quercetin for variety. Or pure Capsaicin." Her smile turns more kindly towards me. "It was a good idea, using Quinine. Only pain might just feel like a battle – a horrible bitter taste just makes things unpalatable. And we got it going essentially on my first feeding. If we keep it up, it'll be easy to train myself to only want to eat when I absolutely have to."

"Oh, good. You are okay." I sigh happily, finally allowing myself to relax. "I don't think demons dream of chemical bitterants and operant conditioning."

"Hey~!" She pouts, and I smile at her, making her pout more. "I'm trying to be serious~!"

"I know, I know…" I say, my eyes slowly sliding closed despite myself. "But, it really is like you. And that's what I was most worried about. That you wouldn't really be Haru anymore."

There is a wet, dripping slosh, and then in an unexpected flash Haru's cold and wet form is pressed against mine in a tight hug that burns every muscle in my damaged and tired body. "I don't think I'm fully the same." She murmurs. "I don't think you can go through something like this and be the same. But I'm not going to abandon you to a world that went this wrong this fast. You need the help." She puts a kiss on my forehead. I can feel her fangs rub against my skin, but I can't bring myself to be afraid. "The two of us will beat this." She asserts. "Whatever happened physically occurred, so it must be possible to use science to figure out what it was. And once we understand it, we can control it."

I feel her leave me, returning to the pool. "I'm going to take us somewhere safe." She says as I begin to drift to sleep. "Somewhere far away… somewhere we can start figuring things out."

I let sleep claim me. Tomorrow. I will face it all tomorrow. For now, I feel somehow, despite everything, safe.


End file.
